The strict-ssl false option is required since it's impossible to auth cached response
from https proxy, which actully acts as a MITM (man in the middle). All other than GET
requests are not cached, so you still be able to publish your modules to npm registry without
switching cache on and off.

Once you have npm configured, start the proxy:

$ npm-proxy-cache

By default proxy starts on localhost:8080 and have cache ttl 30 mins. These values might be
overriden using command line options:

Well, for some reason npm cache works not as expected and cache hits are low. Additionally,
CI servers which run on multiply machines may utilize one cache storage which you can provide
via caching proxy.